Flux



. basic oxides other than that of zinc.

of the low melting point of this flux, I may in- Patented Sept. 20, 1949FLUX Ray Andrews, Washington, Pa., assignor to B. F.

Drakenfeld & 00., Inc., New York, N. Y., a corporation of New York NoDrawing. Application April 10, 1947,

Serial No. 740,709:

2 Claims.

My invention is directed to the production of a flux for glass colorshaving (1) a melting point below 1150" F., rendering it suitable forapplication to glass articles, (2) a coefficient of expansion of .000009making it satisfactory for use on glass of comparable coeflicient, (3) afair chemical stability and (4) not subject to discoloration by theaction of reducing agents or by sulphides.

Most glass colors and enamels contain lead, but these discolor under theconditions above referred to, and are not suitable for the purpose Ihave in mind.

My improved flux is characterized by having as its major constituentszinc oxide, boric oxide and silica, and contains only limitedpercentages of On account troduce certain refractory or amphotericoxides, for the special properties which they impart, and still maintaina flux sufficiently low melting for use on glass articles even when theusual opacifiers or coloring pigments are milled in to form a glassenamel. V

The following batch when melted will yield a flux embodying myinvention:

Table I.Batch compositions The above percentages may be departed from toa limited extent. Thus, satisfactory fluxes are found in the followingranges:

Table III Per cent ZnO 40.5 to 49.6 $102 14.5 to 17.7

Per cent B203 16.5 to L120 2.3 to 2.8 {33.0 3.3 to 3.8 5 NazO 4.2 to 5.2

T102 8.7 to 11 In specifying in the following claims the approximatepercentages given in Table II, I mean to include within my claims theranges given in Table III.

It will be noted that the sum of the percentages of the two alkalies(lithia and soda) in the above flux aggregates 6.5 to 8%.

It will be further noted that the soda contents of all of the above fluxis not over 5.2%. I have found that this low soda is of special valuewhen the enamel made therefrom is to be applied to electric lamp bulbsby dipping the bulb in the enamel ground in alcohol, as is the standardpractice. When the soda content is over 5.2% there is a tendency of thealcohol to react with the soda of the flux to form a sodium alcoholate,which when the dipped bulb is fired breaks down to leave a residue ofcarbon on the bulb, giving a grey rather than a white enamel.

This application is a continuation-in-part of my prior application filedDecember 9, 1944, Serial No. 567,536, now abandoned.

Having thus described my invention what I claim as new and desire tosecure by United States REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,063,252 Kinzie Dec. 8, 19362,247,196 Goodwin June 24, 1941

